If you are going to use a term from NT days, I reckon it would be “People of the Way” and later on “Christians”. Granted, there were no Messianic Jews... or Catholics then. If you are going to use modern terms, to justify calling them Catholics, I insist, Messianic Jews would be more accurate.
>> “Granted, there were no Messianic Jews...” <<
.
What then do you think the disciples and apostles were?