NASA: AS11-40-5877

This is supposedly the first footprint on the moon.

NASA makes no such claim.

Armstrong did not photograph his first step. The subsequent activity around the forward footpad would have quickly erased the first footstep.

This photo was taken at approximately 110:03:00 GET by Buzz Aldrin as part of an experiment to test the characteristics of lunar soil. He first photographed the area before the footprint. Then he took a step forward to make this print, then stepped back again to photograph it. He also took another photograph nearby with his boot in the picture after having made the print. [ALSJ, Apollo 11 photo commentary]

Why does it look like The toe curls up?

The bottom of the print is not planar, as the shadows of the tread ridges suggest. The lunar surface boots had flexible rubber soles and adjusted to the contours of the surface like any other footwear.

Buzz took this footprint especially so he could photograph it. He placed his foot forward, rested his weight on it, and then removed his foot. Try doing this yourself. Stand upright, take a step forward, and then pull your foot back. If you do this without consciously controlling, you'll notice a tendency to push off with your heel. This would cause the heel to dig in slightly deeper, as we see in this photograph. The photo bears the characteristics we expect knowing how it was made. [Ibid.]

How can a footprint cast such a big shadow?

The sun was very low on the horizon. Shadows should appear exceptionally long. The astronauts reported that their boots penetrated as little as an eight of an inch (3 mm) to as much as three inches (7 cm), with an inch being the most common penetration depth reported. [Reports11b]

At a sun elevation of 9 degrees [NASA document M-932-69-11 (1969), Table 2] a one-inch (3 cm) deep bootprint should cast a shadow approximately six inches (15 cm) long on a level, planar surface, actually longer that what appears in this photo. This footprint is probably shallower on average than one inch.

It looks like it's just sitting there on the ground, not imprinted like it should be, like it was made of clay and then placed there.

Any footprint in a particulate material will displace the material to all sides. This should be visible in the photograph as a raised ridge around the print, not that different from the rims of craters.