A key maxim is that you only roll when the result is in doubt.
I gave this a lot of thought when trying to square how those fighters with modest mental stats became kings.
You guys are being insufficiently sneaky with Fireball, especially on the DM side. Consider the healing effect on an Iron Golem. Consider the BBEG using a fireball in a room to burn carpets and wall fabrics to uncover Glyphs of Warding or Symbols or both.
I thoroughly enjoyed it. He demonstrates with visual examples. He even suggests improvements or alternatives like letting a whip trip people. But the thing's an hour long so I can't really summarise safe to say it is worth your time.
This is an hour-long video by a HEMA practitioner far too complex to summarise.
Some very interesting comments and analysis about reach, throwing, martial vs simple, and much, much more.
Look up Scottish legends of mermaids: they can take human form but have a shawl or skirt which allows them to turn back into mermaids. If the garment is stolen then she is stuck in human form. A possible plot bunny for you.
How does the canonical spear and shield build fare? In 2014 5E it was good because you could use Duellist for bonus damage and PAM to get the butt strike of the spear as a Bonus Action.
Matt Easton has just posted a video on pollaxes and one of the things he says is that they seem to break a lot. Languettes seem to be the main counter.
I heartily recommend Tod Cutler's Lockdown Longbow and Arrows Vs Armour videos, and those videos that feature Joe Gibbs.
https://www.youtube.com/@tods_workshop
I can't seem to embed a YouTube short, so here's the URL: What’s the point of a tiny shield?
The presenter briefly explains why shields are different sizes. And moots dual-wielding shields.