I don't want to endorse dolphin fucking or whatever but idk if we can necessarily very accurately map non human intelligence onto stages of human intelligence development. Like human children can idk stack blocks but they're also very emotionally volatile and forgetful. Whales can't stack blocks but they have a lot of emotional stability, good memories, and large stable social groups. How do you map between that? They're not human.

In some ways non human animals appear very similar, especially other mammals and their social relationships and emotions. In other ways they appear very different. They're their own thing and I think overly simplifying their minds by trying to work out some human age equivalent will just mislead us. It's not like a pig that can do calculus would suddenly become a reasonable romantic partner haha.