I have flipped through the forums a little and watched some videos. If I miss out any thread that would answer the following pls link me there. Thank you.
So…based on what I observe what is worth crafting:
Are the following worth crafting?
And are the jewels (except diamonds) of any good use (since mythics are the most valuable and require diamonds not others)?
Side track: What weapons are worth using ingots on?
Celestials and Runics are kind of a shrugworthy decision.
To get a Celestial, you have to spend a bunch of jewels that aren’t diamonds. There’s not a lot of other things to do with those, so I can’t think of a good reason to say no.
To get a Runic, you need to spend some souls and a Major. I’ve got 10x the Majors I need, and I don’t care about souls anymore, so why not? My main concern here is I’ve never really been short on Runics for something I needed, the reason I’m “short” now is I’m trying to trait every troop.
I’m not even sure on Ingot crafting. Since the exchange rate is 10:1 and takes souls, I think unless you are in the final stages of late-game it’s not a sensible goal. Mythic/Legendary ingots are the ones that upgrade the best weapons, and you can get plenty of those from Delves. Epics are the hardest to get, but I’m really having trouble naming a must-have Epic weapon.
I agree with Slypenslide if you are querying as a high level player. Priorities change somewhat if you are not. Celestials are as rare as ascension orbs and epic ingots and there are times when you urgently need to forge traits for strong troops. This often requires celestials to forge the 3rd trait so it’s always worth having a stash or the gems to craft them. NEVER waste rubies etc to craft pet food. Save them for crafting the celestials and the weapons in forge. Avoid using celestials to craft arcanes. Far better to explore a relevant Kingdom despite the grind. You can always pop a wisdom orb if you must acquire a 3rd trait. Lesser ingots (common, rare, ultrarare) should 1st be used to max the associated weaponry and then you can just ascend those that follow in forge. Epics are what you are going to need to forge in the long run. Delve and faction events will give all the legendary and mythics you need. You also get them from tier purchases in certain events so as long as you delve regularly you will have plenty to boost the weapons you need and want to. No need to forge these at all. Runic stones are worth crafting when the troop you are traiting deserves the expense. But otherwise I would hold onto them to trait other troops in general. Other than that, avoid using ascension orbs for general boosting (eg ascending boss killers in raid) if you have any long term plans to forge zuul. Celestials, epic ingots and ascension orbs are like gold dust. Use wisely.
Is there any use for lesser ingots? I’m a returning player so I have a large stash of legends but almost no mythics (left when mythics just came out) 
Do you mean almost no mythic troops? Legendary and mythic ingots were released at the same time.
Edit: to answer your question, use lower ingots to upgrade lower weapons. You’ll eventually want lots of fully-upgraded weapons for kingdom progression, and those weapons are low-hanging fruit.
Yup sorry for the confusion.
Rope Dart!