Bill Zebub
“It’s probably Matt Mercer’s fault.”
Indeed.
I also grew up on Arthurian myth. Galahad's strength was as the strength of ten because his heart was pure. Not because he woke up every day. looked in his spellbook, and cast Giant's Strength. When The Green Knight let his head be cut off and put it back it wasn't because he was using an anti-decapitation spell or a death ward. It was because he was who he was.
I also grew up on Greek myth. When Hercules tagged out Atlas and literally held up the world on his shoulders it wasn't because he cast either a super-strength spell or cast Telekinesis on the World. When he cleaned the Augean Stables by rerouting two rivers he didn't reroute them by casting Control Water. And yes he was a demigod - but so was Circe. If demigods aren't allowed for inspiration we should cut the wizards back to realistic inspirations as well.
I just don't get the desire to turn the back on D&D's inspirations and declare that anything going above and beyond the norm must be a spell.
Heracles also had a full on king of the gods for a dad. Might not be the best example.