Watermelon seeds are very healthy for human consumption and very safe too.
Watermelon seeds contain a lot of health benefits so if you want to go ahead and swallow those watermelon seeds.
My dad used to tell me when I was a kid that watermelons would grow in my stomach if I continued to swallow watermelon seeds but he was just joking with me at the time.
Watermelons will not grow in your stomach from eating watermelon seeds.