This film, in my opinion, can be considered similar to Mary and Max. Both deal with claymation and both films have darker themes in terms of what is normal for animated movies, but they aren't so dark to say that kids shouldn't be able to watch them (like Sausage Party, for instance).
If anything, this would be an important film for kids to watch to try to understand the struggles of being an orphan and redefining the meaning of family in this context.
This was a good, cute film to watch, and I wouldn't mind owning it. To be honest I felt that just a little more effort on the humor would have made me love My Life as a Zucchini. Also, it's a good story but I don't think it had a great climax.