they just seem to be the exact default “lifting with your back” manoeuvre that everyone is always told not to do
I get a bit sick of the scare tactics around deadlifts. The varieties of deadlift are all quite technical, but they are very very good for strengthening your back, glutes & hamstrings - the whole posterior chain.
And the cause of "bad backs" is far more likely to be a weak posterior chain than doing exercises with good form and lifting as heavy as you can manage for say, 3 sets of 5 reps (or whatever pattern feels OK to you).
You can feel your way up to your heavy weight by doing ascending sets. Using dumbbells start with an easy weight, as a warm up set, then try going up by 1-2 kilos each set. Try to finish each set with a couple of reps in reserve. Then next time, you know you can start (or finish) a bit heavier.
You need to challenge your muscles with weights that are at the edge of your capacity, then give yourself recovery time, which is when muscles grow & get stronger - in response to stressing them!
With good form, as @MellowSubmarine and @PacificState describe, you'll get a good strong posterior chain, which is the best defence against an injured back!
Hinge, hinge, hinge.
MegSquats video on different kinds of deadlifts is really good:
(I rate Meg - her stuff is what she herself does & her technical coaching is excellent - for YouTube)