@givemersspls
To answer your question, you're overanalyzing things. This isn't meant to be some deep introspection on Japanese societal norms with a moral of "don't discriminate;" it's another staple of the genre (find an even slightly edgy isekai, and racism against demi-humans exists; just look at Shield Hero this season). Also, Japan is quite accepting compared to many countries around the world (Eastern Europe, not to mention the Middle East). "Accepting [differences]," is not something the audience of this is focused on.
@yldDavid
You're also reading too far into things. The summoned heroes (Hajime and his classmates) are without a doubt Asian. If, like you are right now, try to include them in the "everyone's an attractive white person" conceit, you're missing the point; that's just due to tradition in regards to how animanga characters are drawn and colored. There's also an inconsistency with your logic: you state that you don't think being unaccepting towards foreigners is a bad thing (basically approving a perceived notion that Japanese people are like this), but that clashes with your idea that every character is an attractive white person. If the Japanese were like this, then they would be extremely nationalistic (something that hasn't been the case since arguably the Meiji Restoration), and draw characters looking like asians, not some white dude (again, the way they are drawn is more rooted in tradition than anything else). Finally, stating that the US is just some blank slate country with no culture that others devolve into when there's a melting pot is wrong. There are so many things that are "distinctly American" and ingrained into our culture that to state there is none is disingenuous (cars, military spending, various personal freedoms and liberties, etc).