Improved will be a matter of opinion of course. This can vary if you want specific things like still having a brothy soup, was it too bland, are you keeping it veggie on purpose, is spicy ok, are you limited to just those veggies, etc.
If you can give some more details on what you want it will give us a better understanding of your target.
Now all that disclaimer outta the way I’d say cook everything more.
If you’re staying 1 pot stove top very first thing is add a bit of oil then go at it with your herbs. Do not skimp you want a flavoured oil & base.
For the pic I see up there (imo) I’d do a good pinch of oregano, rosemary, 1/2 pinch of thyme, 1-2 bay leaves, if you have any Cajun/meat seasoning kinda powders give them a shake in. If you don’t have garlic use garlic powder, black pepper. I don’t add salt here. Also if you like cayenne, etc add a pinch now.
Colour that oil! But don’t burn it
If bacon is allowed now’s the time to add in 2-3 chopped up slices. If not never mind.
Also if bacon is an issue any meat you prefer can work either slice it up to cook or leave it large and cook it low and slow for the time it needs. (Bone in meat is great).
Now veggie size is definitely your call I often do more stew size pieces but mom used to always give me flack for not cutting them enough. Diced will definitely sautee easier but again depends what you want. Just cause you want diced onions doesn’t mean you can’t have chunky carrots so you do you.
But it’s definitely time to toss in your smashed garlic if you use whole garlic. Along with your onions. Once they’re coated and under way in with the carrots & celery.
If you want spicy now is the time for a diced jalapeño or chilli pepper but your call.
Next is your can of tomatoes. I like the diced herb & spiced ones or ones with the seasoning cause is all been in there kinda marinading more or less. Just enough water to rinse out the cans then swish and dump it in. Cook that down get a bit of that water off let things richen up.
Once it’s getting thicker if you have a box of Campbell’s broth (yea it’s a cheat) dump that in and add your peas and corn, etc. if not a couple cans of water will do.
But then you have to let it simmer and give that water time to become broth. Let it simmer for an hr if you can on low.
Also if you don’t like pieces of tomato (which should dissolve just fine in time) then skip it earlier and add a can of condensed tomato soup now and stir it in. It will make the broth a bit silkier but won’t give you the depth of flavours. Also make sure you stir it so it doesn’t stick to the bottom of the pot. (I know it’s another cheat)
As stated above now a couple shakes of soy sauce will give you the salty seasoned flavour but richer. However, if steak spice or and mixed seasonings are already in there careful you don’t make it too salty (I’m not a big salt guy)
Once that smells like heaven bowl it & don’t burn your tongue. I recommend you make biscuits while it simmers cause that’s delicious but whatever your preference is go for it.
That said if you want a thicker soup not a brothy soup grab a stick blender and go to town on the whole pot/ or batch it onto your bigger blender of course.
If you want creamy add some cream to your puréed soup until it’s hot then serve it. I personally never do this (I’m not a big dairy guy)
Top with Parmesan if you want to and enjoy.
PS
If you’re asking us how to fix the batch you already have then I miss understood the question but some of my points still stand.
If you’re wanting a more deep roasted flavour that’s an oven soup not a stove top soup so different again.
Good luck & let us know
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. I just tend to make a soup and it lasts a while and gets reheated, etc. 
