Inclusivity, inclusion, and inclusive are terms which are used as a part of the same phraseology as the word, “diversity,” and are exploited to both denote and connote a new kind of opening up of something once exclusive, perhaps a new, integrative form in American culture from the 20th Century attempts at assimilation.
The root of each of these words is the word, “include,” which means, to take in or comprise as a part of a whole or group.  Of course, everyone who understands American English understands this word in its broadest sense. But the terms, inclusivity, inclusion, and inclusive have specific meanings related to previously segregated spaces and places of Whiteness, according to Merriam Webster and Oxford Dictionaries, without actually acknowledging Whiteness itself as the exclusionary rationale:
Inclusive: including everyone, especially allowing and accommodating people who have historically been excluded (as because of their race, gender, sexuality, or ability). 
Inclusivity: the practice or policy of providing equal access to opportunities and resources for people who might otherwise be excluded or marginalized, such as those having physical or mental disabilities or belonging to other minority groups. 
Inclusion: The action or state of including or of being included within a group or structure. 
In my view, if these terms represent anything inclusive, it is the “inclusion” of simply more feel-good neutral wording in a culture trying desperately to give the illusion of neutrality, normalcy and naturality, with no significant impact on policies, laws, or regulations, and only providing tepid relevance in the vernacular of racialized American thought. Even with evidentiary proof of the day-to-day impotence of these terms, no one even questions the veracity or legitimacy of being inclusive or of inclusivity and inclusion, relative to the meaning of diversity in America.
The case for the use of these terms today is tragically ironic, considering the present state of the country in terms of its negligible efforts on behalf of desegregation during the 20th century. Indeed, these words are not even new. Inclusivity as a term was introduced in 1920, achieved its most popularity of usage in 1998 and has been dropping since, while the term, inclusive dates back to a 16th century medieval Latin derivative, and reached its peak in popularity in 1934, then dropped dramatically until about 1997 and has been dropping ever since. The term, inclusion, is from the 17th century Latin word, inclusio, and also peaked in popularity in 1997, dropping steadily ever since.
One would never guess how infrequently these words are actually used since they essentially replaced the 20th century words, integration and desegregation as the representation of accommodations for, or practice of, providing equal access for everyone considered by Whiteness as diverse, or different, and appear to be the only words that are, at least in the abstract, the most adequate in the 21st century for expressing the desire of people who utilize them for what they are supposed to represent in their meanings.
What must be taken into consideration, but generally isn’t, is the obfuscation, lip service and window dressing White Supremacist culture in the United States has allowed the more liberal white people in the culture to present through terms such as these since the Civil Rights movement, if not in practicality, at least as an illusion of the meanings, for purposes of acknowledging the precepts of the Constitution. It must be understood that although these terms sound like a grand endeavor of America to live their creed, these terms have come to be merely some of the same kinds of what I call the “sweet bullshit” in an otherwise categorically suppressive, oppressive America, with absolutely no intention of subscribing to the meanings inherent within the terms or their application in reality.
Nevertheless, at present, there is an entire cottage industry built on the backs of diversity and inclusivity. According to Jeanette Settembre, writing for MarketWatch in 2019, diversity and inclusivity training is an industry raking in upwards of $8 billion dollars a year from U.S. corporations. While there are certainly genuine, thoughtful groups, companies and organizations trying to build upon the meanings of these terms and train people in education and industry, not all trainings “have a significant impact on changing workplace behaviors, and can even fail to increase inclusivity at work.”
Moreover, these terms can even be considered simply more euphemistic code speak for Race as Color. When Diversity is added, it becomes a gentler word than “other” or “different,” and can be used by Whiteness to herd just about every conceivable different, and previously intolerable aspect of the culture together. Coupled with the terms inclusive, inclusivity and inclusion, they provide a milder expression than the now derogatory connotations of desegregation and integration of the 20th century. Their use today is a rather successful method to corral all people considered “colored and others” into one enormous stall, much like the term, people of color (POC and derivatives) places EVERY non-white person into one huge classification of “colored." This status maintains the exclusivity of Whiteness because of its own synonymy of colorlessness, since the very definitions of inclusive, inclusion and inclusivity relate primarily to marginalized people of color, and others, NOT the dominant culture.
All the terms give the impression of genuine accommodation, but to the trained eye looking through the lens of White Supremacy it is a fallacy, just like the ideology itself; the paradoxical framework of simultaneous reality and fantasy. And through inclusion and diversity as expressed today, White America can continue living within a fantasy of an inclusive nation while remaining outside of the realm of inclusivity and inclusion, because they do not include themselves among the diverse, will never include themselves among the diverse, and will therefore never be inclusive, but will maintain themselves in a space where segregation persists, separate and perpetually exclusive.