I have no idea why you equate “same” with “white,” but diversity is not limited to skin color or defined by race.
Immigrants have been assimilating into the American culture since America became a thing.
Diversity and division are two wholly different things. If immigrants don’t assimilate into the common goal and idea of the American Dream, (baseball, apple pie, an education and a house to live in) and insist on bringing their allegiances with them and applying them to our general society, it’s no longer immigration but an invasion. Conquering Armies impose their will, not immigrants.
Look to France and Sweden and Germany, where No-Go zones exist as an example of non-assimilation.
You bring up the Constitution in your response, but before the Constitution and it’s full protection is available to an immigrant, they must become a U.S. citizen and take the Oath of Allegiance:
“I hereby declare, on oath, that I absolutely and entirely renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty, of whom or which I have heretofore been a subject or citizen; that I will support and defend the Constitution and laws of the United States of America against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I will bear arms on behalf of the United States when required by the law; that I will perform noncombatant service in the Armed Forces of the United States when required by the law; that I will perform work of national importance under civilian direction when required by the law; and that I take this obligation freely, without any mental reservation or purpose of evasion; so help me God.”