 If you liked
Alps no Shoujo Heidi
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 ...then you might like
Kemono no Souja Erin
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Firstly, I wanted to make a more complete recommendation, but that would be a spoiler for Erin.
Heidi and Erin (to some extent) are literally very similar, and I don't doubt that the author of Erin was inspired by Heidi for this, as it is a classic.
Let's go: Everyday life is often relaxing with the child protagonists, in a certain part of the story both protagonists go to school, they take care of animals... I wanted to say more, which would complement a lot in how similar they both are, but that would be a spoiler from Erin.