There was actually some logic behind it.
Back then many people were getting their first PC and a lot of them had never used a mouse before.
So they included these particular games because they're like mouse training. In minesweeper you develop the skill of clicking on small squares, and differentiating right and left button clicks.
In solitaire you got to practice holding down the left button and dragging things around the screen.
A mouse seems pretty intuitive for those of us that grew up with computers. But I remember showing my grandma how to use the computer and it was painful because it took several tries to click on the little x to close the window.