Flooring – Replacing rotted shed flooring without changing foundation

I realised recently that part of my shed floor had sunk. When I pulled up the carpet I found that the wooden floor had rotted away. After pulling away some of the rotted wood it looks (to me) as though the underlying support is still in tact.

I don't know how old the shed is. The property is around 20 years old, so the shed will be less than that.

My question is – to fix this can I simply rip up the rotted wood on top and replace it with new wood?

See below 2 pictures to help explaining. The orange dot in the 1st picture indicates the placement of the shot in the 2nd picture.

The purple speech bubbles indicate what I believe to be support beams just from where the wood lines up and the sound made when knocking the floor.

Edit

Below is an image the shows the interior wall as well as the issue.