Why did my first click hit a mine?

On Minesweeper.now it cannot happen: the board is generated after your first click, so that cell is safe by construction and its eight neighbours are kept clear too. If your first click hit a mine, you were playing a version that builds the board before you move.

Which versions do not protect the first click

Original Windows Minesweeper generated the board up front and then quietly relocated a mine if your first click landed on one - safe, but it did not guarantee an opening, so you could reveal a lone number with nothing around it. Many faithful clones reproduce the original behaviour exactly, including the versions where the first click genuinely could kill you.

What a good first click should give you

Not just survival - information. A first click that reveals a single 4 with eight covered neighbours is technically safe and practically useless. Generating the board around your click, as this site does, means the opening cascades into a usable region of numbers you can immediately reason from.

What about later clicks

Only the first click is protected. Everything after it is on you - and on the board. If you hit a mine on move two, either the deduction was wrong or you were in a position that forced a guess.