Any possible explanation?

I have a 2001 Ford Explorer Sport Trac and the seat belt light stays on. I buckle myself up and the light stays on still. As I drive, it beeps fast meaning I need to buckle up even though I'm. Any possible idea to fix this? The wires and connections all look good and no corrosion.

Looking good is not enough. Test wires and switch for continuity if you know how. No idea to troubleshoot, see a mechanic.

The mechanism inside the latch isn't working

The connector under the seat may have been unplugged. Depending how many warning lights you have, it may also be the one on the passenger side.

Try buckling the passenger seat belt as well as the drivers one.

If you don't know how to maintain your vehicle, then you should not be allowed to drive on the road.

Break the connection to the seat belt latch. Use a meter to ohm the two wires coming off the latch. Probably should be a short when buckled. If not, short the two wires together at the plug, simulating the buckle being latch. If it stops chiming, latch is bad.