Great conversation! The usual Catholic answer against is that, while all creatures that live have souls, only “rational souls” can apprehend God and thus are capable of heaven, once redeemed.
A minority view (and mine) is the we know the creation groans like someone giving birth waiting for the consummation. The creation suffers for the choice of our first parents and longs for the fulfillment of redemption.
Then, consider the tamed animal. Isn’t he more human-like? Even my cat, Clint, has submitted to some discipline and shows some feline love.
So, despite their questionable rationality (which of them would wonder about this question) they show traces of a humanized love. That’s an unquestionable and profound good which ought not to be belittled.
Besides, if I may say so, I don’t think God is looking for reasons to restrict his love and joy. He does far more than we can imagine to spread his peaceful and jocund kingdom “far as the curse is found.”
Miracles do happen.