Call it an assumption if you wish. I'll call it a conclusion based on data.
It seems a pretty reasonable assumption, either way.
But I am perfectly capable of recreating the track.
I can test my model. I can take any random human who still has both legs and feet, remove his shoes and have him walk on a beach and compare the tracks.
Hunters use these techniques all the time to track certain animals. And they are very succesfull at it. Reading your hilarious objections to concluding past events from evidence/data in the present, hunters shouldn't be able to do this so succesfully.
That would not leave the same tracks. The tracks on the beach, first of all, are naked feet, not shoe prints. Secondly, this hilarious bike wouldn't leave tracks that are consistant with standard bipedal walking. It would be a straight line of footprints instead.
The dog would also leave other tracks.
Let's try something else then.
Which of these would you consider the most reasonable "assumption":
- a human walked there
- a bipedal dog with shoes in the shape of human feet walked there
- a supernatural ethereal demon put the tracks there to mislead us