I think there's a few elements to your question.

One is the question: "Does the study of history need to have some practical use or utility in order to justify its own pursuit?"

For me the answer to that question is very clearly "no", it does not need to have such a purpose. That being said, I would follow Marc Bloch in defining history as the "the study of man in time." If that's true, if the study of history by definition tells us something about man and the human condition, that, in my view, does have a profound and intrinsic value that justifies the pursuit of history even if it doesn't necessarily have some "practical" usage.

The second element, is contained in your question "to what extent is it possible to learn from history?"

I might rephrase this in light of the first question as "If history need not have a practical use to be justified, nonetheless can it have such a use that we can learn from?"

Here I would say very clearly "yes."

I'll put aside my arguments in favor of this general point by turning to the specific, third element of your question, which I would read as:

"If history need not have a practical use to be justified, but if it can nonetheless teach practical lessons, what such uses can we derive from the First World War, particularly given the eventual outbreak of the Second?"

I would say that there are many such uses, but that I think you have to be a bit less ambitious in what you're looking for. So when you say:

espite calling WW1 "the war to end all wars" WW2 still happened and preceding that a multitude of different wars that caused non-stop destruction to nations and peoples, so have we really been able to learn from the past and prevent ourselves from making the same mistakes?

If the lesson you want to draw is that WWI was a "war to end all wars", and from that fact that we ought to be able to study the history of WWI and thereby accomplish an end to all war, then no, I would say that's impossible. As complex and as interesting as WWI is, it does not hold the key to all human conflict and therefore can't possibly contain the key to preventing all future human conflict.

But, for example, the field of history can (and does) look very intensively at WWI in order to identify mistakes that were made that contributed to failure to attain a "peace to end all peace" at the end of the "war to end all wars." The outbreak of WWI and the attempted treaty to end it is, for example, basically the jumping off point for the creation of the modern field of International Relations. While we could argue about the efficacy of IR theory, insofar as concepts like "the balance of power" and "the alliance system" and "pre-emption" continue to have real meaningful consequences, we largely have a field that devotes an enormous amount of time looking at WWI to thank for that.

In my own experience and professional life, which I've talked a bit about in various places, understanding the modern or contemporary Middle East simply isn't possible without studying WWI. Knowing, for example, how and why WWI contributed to the creation of Israel, is pretty darn important to understanding why the Israeli/Palestinian and Arab/Israeli conflicts remain so intractable.

Is there some singular lesson that can be learned from knowing that history that could prevent making the same mistakes? I doubt it. For one thing, I don't think it's possible to "make the same mistakes." We make all kinds of mistakes that might have a relationship but can't be the same. And to err is human, so I don't think any amount of the study of history will eliminate human mistakes.

I realize this is all somewhat theoretical and philosophical. I'm happy to try to go into specifics that might interest you as best as I can. But yes, I would argue that WWI is incredibly rewarding to study, and though it's not necessary for it to be useful for it be rewarding to study, but that a vast number of elements of WWI do have practical lessons for contemporary and future politics, policy, and other real world applications.