Sam2 -“The main problem you run into, though, is time. If you assume that the 6 days of creation were 6 24-hour periods, there just isn’t enough time for any evolution. The idea that it is heretical to believe that those days were longer than 24 hours seems to be quite a minority, though supposedly R’ Elyashiv did say it”
Why assume that? Maybe the 6 days of creation are 1000 years corresponding to 1 day of Hashem year. 6 days = 6,000 years.
I don’t have a problem with one animal or creature changing form to another, as long that originally they both were created from Hashem.