Well, I’ve taken a lot of beginners out, and watched them croak, or pearl, get scared, or run out of gas. So at this late date I’ll add my 2 cents.
What does a beginner do, or not do, that we want, or want to eliminate?
One, they can’t paddle, so a really wide board (much wider than their shoulders) is out. If they aren’t required to paddle, then wide is okay.
They pearl a LOT. So a board that doesn’t pearl easily is essential. Light in the nose, wide with lotsa area, a good deal of rocker, and think about what foil makes a board less likely to pearl.
They take off at a slight angle and catch a rail/pearl, and it’s all over. So the nose has to resist catching and then rolling them over - wide with a high rail line.
Stability is essential - how many beginners get sold the latest Joe Hotrock model at the surf shop, then wonder why they can’t paddle or catch waves? There has to be enough board there for them to paddle, unless you are pushing and retrieving them all the time.
More fins on a board not made for high performance are a joke. One fin will be enough to keep the board going in whatever direction it needs to. More fins are more opportunities to catch a sharp edge somewhere it will cut, bleed and hurt their bodies and their feelings.
They will run their boards right into the beach. A strongly glassed-on fin is essential.
It has to be light - micro-groms can’t carry much, nor steer a signigicantly larger mass. Also, a light board hurts a lot less when it blips you on the head. AMHIK.
They’ll get hit by the board no matter how many times you warn them. Both my daughters have. Soft boards!
All in all a light, soft, round, single fin, board sounds like it will do the job. But such a board isn’t “cool”.