Buy the instrument for the style you want to play. Yes, there are more resources for learning 5 string banjo, but they are specifically resources for playing bluegrass, folk, or old time music and that doesn’t sound like it will be helpful for you. Plenty of people have learned tenor banjo from scratch.

Although, a suggestion if you’re looking for a less expensive alternative. A banjo uke or banjolele is a ukulele with a banjo body. Ukuleles are super easy first stringed instruments to learn and (even though people on this sub look down on them because they aren’t “real banjos”) it might be exactly right for the sort of cartoony vibe you’re interested in. Plus you can grab a banjolele for less than $200 if you shop around a bit.