These things happen, mate, with experience you'll fid a lot more ways to stuff up - those that haven't are liars!
My "favourite" is forgetting to refit the rotor after fitting and setting points* in distributors - must have done it well over a dozen (or two) times ...
For the youngsters, back in the Dark Ages, cars used Kettering ingnition, which used a mechanical switch operated by a multi-lob cam which was in the distributor, to operate the coil for the correct spark timing.