Senseless

Time is, of all the things in the world, what has baffled me the most my entire life. I'm not talking about some abstract scientific principles. I'm talking about 12AM and 12PM. Lets examine this starting at midnight.

12 am
1 am
2 am
3 am
4 am
5 am
6 am
7 am
8 am
9 am
10 am
11 am
12 pm
1 pm
2 pm
3 pm
4 pm
5 pm
6 pm
7 pm
8 pm
9 pm
10 pm
11 pm

Since when do we count zero as a 12? Instead of 10 am and 10 pm, should it be 112 am and 112 pm? It doesn't make any sense people!