re: What is the “normal” ratio of mortgage loan vs annual income?

Many people look at their house as an “investment.” That is certainly a valid perspective.

I look at it as a place to live.

Your income will likely go up over the years.
Interest rates are historically low.

I don’t think you are doing anything foolish, as long as you don’t have to move for say 3 to 5 years.

Good luck!

I know others won’t like this, but if you can avoid PMI- do it.