Unless a guy is a serious fisherman 3 knots are essential for getting through life. Add the truckers hitch for good reason even though it's just a farmation of simpler hitches. And I saw that farmation spelling error. It was an error, but an accurate one.
The 3 essentials are
The bowline. Easy to tie. Easy to untie. Strong enough to do most tasks.
The clove hitch. Easy to tie. Easy to untie. Superb in strength, but I would only use it to tie to a fixed object.
This is the hitch most used to tie off safety lines for those who work at elevation in construction and industry. Replaced in today's world by the safety cleat.
Strong and simple, but still needs an additional half hitch to keep it from "rolling out" if used for a safety line or if the angle of pull can change.
The tent hitch. Strong. Simple. Easy to tie and untie. And adjustable without unintentional slippage.
Adjust this hitch for tension and it will remain tight until either you release it, the rope stretches, or an end it's tied off to moves.
If you find it looser than you want it, you can retention it in about a half second without retying.
