By the way, if you have good reviews on Airbnb, those can help convince a homeowner to give you a shot even if you have no reviews on THS.com. (I am a "host" on THS and have seen some sitters link to their Airbnb profiles.)
As a somewhat nervous home and cat owner I never consider applicants unless they have at least three five-star reviews (these generally show that the person is caring with animals and also takes good care of the homes they are entrusted with). That said, there have to be hosts our there who are willing to give new sitters their first break.
As a host I have 6 sits under my belt and each has been a five-star experience. Here are some insights: I only consider applicants who 1- send a coherent message with their application, showing that they've read my listing with care (many do not; my listing states that these will be automatically rejected), 2- have a lot of cat-sitting experience as evidenced by their reviews (many sitters have experience with dogs and not cats), and 3- are self-professed cat-lovers (extra points if they say they have/have had their own). Once I've verified that the candidate(s) look good on paper, I always have a zoom call and only then, if my gut feeling is that we are a good match, do I offer them the sit.