Most cultures have something that can be classified as "historical legends" and these are featured in what we often refer to as "classical mythologies." Historical legends are legends - narratives told generally to be believed. They are historical in the sense that they are set in times that people regarded as an approachable or nearly approachable past as opposed to a primordial past when the world/universe and the pantheon of gods were first being created - or when humanity was first created and acting out its first steps.

The characters of historical legends run the spectrum of purely fanciful to based loosely on/taking inspiration from a historical character (or characters) to based on a fairly well-known character, but recounting escapades that are more or less fanciful. The examples you cite can be placed on the first end of the spectrum I describe.

There are often speculative attempts to link these fantastic heroes and their escapades to historical events. These attempts are, by definition "speculative." One frequently finds articles that indicates, "historian links the legend of (fill in the blank) to real historical event." This inspires a great deal of press coverage, followed by questions submitted to /r/AskHistorians.

The problem with this speculation is that it cannot be proven and it is usually just someone who "had an inspiration, i.e. an idea." Without proof, we are really nowhere.

Could the feats of heroism described in classical mythologies be based on actual events? Perhaps, but I have not seen proof that this is the case.