Do humans have a gravitational field if so, how strong

Yes, every living or nonliving object has its own gravitational field. However, a human's is so small it would be impossible to measure.

I'm pretty sure that you have mass. When it comes to gravity, anything that has mass behaves exactly like anything else that has mass. Any two of them are attracted to each other, with a force that's proportional to the product of their masses, and inversely proportional to the square of the distance between them.

Now, if you have mass, then you have weight ... it's the answer you give when somebody asks "How much do you weigh?". That's the force of gravity between you and the Earth, pulling you toward the center of the Earth. But it doesn't stop there. There's also a force of gravity pulling the Earth toward the center of you. The strength of it is EQUAL to your weight.

Your weight on Earth is EQUAL to the Earth's weight on YOU!