Yeah, in my experience regardless of country the people who want to travel are not the same ones that want a regression to isolationist BS. Especially with the US, where going to another country on holiday is not a casual thing (like with the massive influx of tourists into the spanish coast in summer, for example), the people who are there are generally are the ones that want to be there and are curious about other cultures. I don't know if that 1:1 correlates with being "nice" or "sane", but it certainly sets people up for not being intolerant and that's a big part of not being a jerk.

Also I was curious and looked up the figures on travel rates. According to these rigorously validated sources (i.e. "they looked pretty good to me") it looks like:

11% of US citizens have never traveled outside of the state where they were born. ^[1]^
27% of US citizens have never been outside the country^[2]^
29% of US citizens currently live in their home town^[3]^
^(^^source^ ^1^^)^ ^(^^source^ ^2^^)^ ^(^^source^ ^3^^)^

This is in a surprising contrast to the EU demographics, where:

37% of European citizens have never been outside their home country^[1]^
^(^^source^ ^1^^)^

(I could find no sources for the other statistics for Europe, I'm sorry!)

Important Note:

There are other commonly cited surveys (from far less reputable research groups than Pew, it really should be noted. One of them is literally just an ad for an AI language-learning app) which put the amount of americans that have never left the country closer to 40% (forbes) or 42% (preply) so ymmv with these numbers. Personally, I trust pew over Forbes or some slop factory, but for transparency's sake I felt I should include them!