AS can when first detected appear to be a heart murmur, but it is a problem that develops over long periods of time as those who have it are usually asymptomatic. Bill Paxton the actor (Titanic, Aliens) had it, underwent surgery and died in 2017 shortly following the AVR procedure. Look him up.
It is not common but there are a few heart problems resulting from fetal circulation not being properly resolved at birth. I am not an Authority, but I have studied the matter just a bit.
I was born with a bicuspid aortic valve, my understanding is that it’s just between 1% and 2% of the population have this defect. Because it doesn’t fully open it causes blood flow abnormalities that result in calcium buildup on the valve. I didn’t know about it until I was in my fifties when I went in to the doctor because I couldn’t run as far anymore. I ended up having the AVR procedure and it was replaced and Edwards synthetic valve that is engineered from bovine pericardial tissue. That was about 4 1/2 years ago.