Lots to unpack here:
1) You and I differ on the definition of "good" when it comes to films, based on the definition you give here. For me, a film can only start to be good if all the component parts - performances, script, direction, cinematography, choice of locations, visual effects, music, costumes, art direction/set direction, editing and so forth - are good. It certainly cannot be "great" until it has "matured", like a good wine. At least ten years is my rule of thumb. By that standard, a 10/10 rating for a film like The Super Mario Bros. Movie is objectively preposterous, especially considering you have admitted the flaws yourself (ie it's one long commercial and the plot is merely good enough, which frankly wouldn't cut it for me, even if I was steeped in Nintendo lore).
2) That a film is enjoyable for you and indeed your whole family doesn't make it objectively good cinema for the reasons I've outlined above and in this article. But it hardly matters what I think. If you enjoyed the film, and if your family enjoyed the film, I'm glad. Other opinions are always available, if mine are not matching yours in this instance. :)
3) I think it is entirely possible to acknowledge that one enjoyed a film, whilst also acknowledging it is flawed, perhaps deeply so. I can think of several guilty pleasure films that are objectively rubbish but I nonetheless enjoy (Highlander, Supergirl, Condorman, Angels and Demons, Bad Taste, The Blob, Hudson Hawk, A Fistful of Fingers, Flesh & Blood, and various others).
4) Aftersun: If you read my review, you'll see I clearly state it isn't for everyone. I also clearly state that it isn't a film with a driving narrative, more a meditation, a reflection, a mood piece. I found it profoundly, devastatingly moving. Others didn't That's fine. Not everyone is wired for cinema that exists outside three-act archplots. But I believe Aftersun is a work of genius for many, many reasons far too numerous to get into here, and again, judged by my own criteria, I consider it a masterpiece and stand by that. In years to come, once it has "matured", I believe it will be revered in cineaste circles, though perhaps not among general audiences (again, why I stated in my review that it wasn't for everyone - I do try to keep the audience in mind in all my film commentary).
I think that covers everything. :)