Judges 11.24 does not view Chemosh as just as valid as Yahweh. Chemosh was the national god of the Moabites. he was considered by the Moabites to bring victory in battle (as all ancient cultures, including Israel, considered that their deity functioned as the divine warrior, giving them victory).

Basically Jephthah is saying, "You conquer whatever your god gives you just as we conquer whatever our God gives us." That doesn't mean he's putting the two on the same level. In a similar head-to-head in 1 Samuel 17, David considers the Philistine's god to be a false god and not real (1 Sam. 17.36, 46). So also 2 Chron. 32 (esp. v. 19). Here Jephthah is saying, "Don't be so greedy for our land. Go away and leave us alone!" (Judges 11.25-27).

> The mainstream view is that the Torah was composed as political propaganda after the northern kingdom of Israel fell to Assyria.

This is just a bunch of malarkey and has nothing to do with your question.

> And the Torah was henotheist. Not monotheist.

This is the position of some, but is unprovable. And it has nothing to do with your question.

> The monotheistic elements in the Torah were only inserted after the Babylonian captivity.

More malarkey. Unprovable. Has nothing to do with your question.

How do you explain Judges 11:24 which views the god Chemosh just as valid as Yahweh?

The mainstream view is that the Torah was composed as political propaganda after the northern kingdom of Israel fell to Assyria.

And the Torah was henotheist. Not monotheist.

The monotheistic elements in the Torah were only inserted after the Babylonian captivity.