I want to refer my brother to Fiverr so that he could sell stuff so that we could both get money because I referred him instead of him buying something and just getting me money that way.
He can just sign up for an account. There’s nothing one can get by bringing another seller onto the platform (as far as I know).
Fiverr would never have a referral program for onboarding new sellers because that doesn’t mean they will get sales and because they already have a surplus of sellers. They have no reason to want more of them. Plus, if people could get a referral commission that way, people would make Fiverr accounts just to get their friends referrals and it would flood the platform with dud sellers/gigs.
Referral programs are based on sales only.