I also remember learning in an intro linguistics class that babies are born capable of producing every sound, but that as they learn their native language, their vocal cords specialize and they lose the ability to make sounds which don't exist in their language. So yes, all languages are 'simple' enough that a baby can learn them, but there are also reasons why an adult might have trouble rolling their R or pronouncing the Hebrew 'ch' properly
I teach a Norwegian child whose baby sister has a name which sounds very different when they say it to each other compared to when they say it to us. It's like they have pretty much accepted that nobody in North America will say it properly (it sounds like a sort of trilling i sound when they do it) so there is a lot of 'her name is [bird chirp noise] but you may call her Angloversion.' I wonder if, should they decide to stay here, they'll be sorry they didn't choose a more English-friendly Norwegian baby name
I know my stepbrother has expressed regret about one of his kid's names---it's very popular in the Jewish day school circuit, but nobody outside of that community can say it properly, and there are some lovely Hebrew names that are much easier...