Frontline control caster?

[LudicSavant]

How would a variant human(moderately armored) lore bard do?

Lore Bards do well. In fact, I daresay their kit may better suit a main tank than the Valor Bard (whose Bardic Inspiration can only boost a different player's AC, and even then only if you're buffing them ahead of time... so it's only really reliable if you know beforehand that someone else in the party is going to draw aggro, and be tanky enough to get good dividends from a stacking AC. You know, like if someone ELSE is a frontline controller).

By contrast, a Lore Bard's Cutting Words is reactive, can defend yourself or others, and is more versatile than just an effective AC bump -- it can also cut an enemy's initiative (potentially losing them an entire round, effectively), or cut damage rolls (especially effective against things where one damage roll causes damage multiple times, such as with AoEs), or synergize with Armor of Agathys (since Cutting Words cuts damage rolls), or ruin counterspell rolls, and the like. And extra Magical Secrets can grab you nice frontliner tools. It also benefits more than Valor from a 1 level Hexblade dip, if you wanna go that route.