Answering this one is a doozy. It has a lot of assumptions that need to be unpacked.

First and foremost, I won't comment on current Jordanian demographics, due to the 20 year rule. I will say that Palestinians have formed a large part of Jordan's population since 1948, and even moreso following 1967. You'll notice that those are the years of wars with Israel. That's because a lot of Palestinian refugees were forced to or fled to Jordan during those wars.

Also of note is that when Jordan annexed the West Bank in 1948/49, following the first Arab-Israeli war and the invasion of Israel, it gave all the residents there citizenship. That meant Palestinians in the West Bank could move to any part of Jordan, and remain there.

Given that Jordan annexed the West Bank and all of its refugees, as well as taking on other refugees besides, their population took on a huge number of Palestinians. Jordan wanted to keep the West Bank, though. It didn't want to create a distinct Palestinian state because it viewed itself not only as the rightful inheritor of the land, but also as Palestinian itself.

Indeed, it wasn't until 1988 that Jordan really abdicated its claim to the West Bank, though the claim was largely toothless after the 1967 war, when Israel took the West Bank from Jordan. The king of Jordan, in 1988, said that "Jordan is not Palestine", but prior statements by Jordanian leadership reveal their ideas about the land. For example, the Jordanian Prime Minister insisted that Palestinians freely joined themselves to Transjordan (Jordan) in 1950, and that any attempt to undo this was wrong. He also said in 1959:

We are the Government of Palestine, we are the Army of Palestine, we are the refugees.

You can see here a statement by the Jordanian delegate to the United Nations, where he talks about the connections of the entire Arab nation, and particularly those of Palestinians and Jordanians. But it goes deeper than that, as in 1981 King Hussein said, "The truth is that Jordan is Palestine and Palestine is Jordan".

This view is not necessarily one that was popular among Palestinians themselves, but it's important to know to understand why Jordan made no move to create a Palestinian state between 1948-67 when they controlled the land.

The other part of your question seems to be, why did no one recognize Jordan's annexation of the land and call it all a Palestinian state, correct? That's what you're asking? Part of the reason is that the Arab League opposed it completely. Much of the Arab League had their own plans for the land, and viewed the Jordanian annexation as antithetical to their goals. Without Arab League support, it couldn't be viewed as a solution.

The other reason is that Jordan controlled it during a time before the two-state solution became the solution of choice at all. Palestinians and the Arab world maintained that only the destruction of Israel would do for any kind of peace, which meant trying to get Jordan to keep the West Bank wouldn't really solve any type of problem.