> in the first case, you have to accurately remember the past

Right, as a matter of (relatively trivial) cybernetics between man and machine, it rests on the weaker parts of the human.

TBF, it'd make a lot more sense if every command on screen (or given the timescale perhaps teletype paper prinout) was already labeled with the necessary number.

You can just add something like (\\!) in your PS1 and get just that.

PS1="(\\!) \[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ "

as a full working example