In Spanish, we have a word for a little toy that always stand up, “tentetieso”.
I want to search for those toys in English, but I can’t find the correct word or specific description to find them.
I’d call that a Weeble Wobble or Weeble but I think that’s a trademark usage of a roly-poly toy (as GileBrt notes as the generic term for one) much like Hoover is not only used for vacuum cleaners that are made by Hoover but other manufacturers too. Whether this is a UK convention though I’m unsure [Judging from comments it’s AmE too].
I’m also certain that somewhere I’ve seen a cartoon or kids TV character roly-poly toy that even says “Weeble Wobble” as it bobs back and forth. (Also Weebl)