Hi
As you can see, I've abbreviated your post a little...I hope you don't mind
I also consider myself as a 'mature' player too, (73 yrs old here). I have no interest in PVP either...but still, I have the choice of 'risking it' if I choose to play in open, knowing the places and situations where this might occur
is a calculated risk, a balance if you will in the sense of what I'm prepared to lose...or gain, which covers several scenarios, which I won't go into here. Suffice to say I mainly play in the Solo mode, but not always. I'm happy that there is an open mode though, it's another choice.
Okay, lets take your experiences with 'Space Trucking'. Yes, been there (I still do on occasion). My own experience's?....I eventually learned that if you want to take those higher paying trade missions (and also 'stack' them) then as others have said you either learn to wake out successfully when interdicted or the other choice is fight, but there are also other ways to survive the encounter, which can be interesting and fun.
I choose to fight most of the time, It's quicker, I usually get some good bounty credits, and also because no pirate is going to take my hard earned cargo!...if my shields start to go down quick I'm perhaps going to run...it's less expensive... but that doesn't happen very often.
Anyway, that means I need a ship that's up to the task, I've never bought a T9 btw. my early experiences with trade and / or courier missions I used the Python, Cobra or Imp. Courier. Only buy what you can afford to lose really, I couldn't realistically afford anything bigger than those three ships at the time, and taking into account the rebuy cost as well....a T9 wasn't going to be a good choice to my way of thinking at that stage.
Nowadays I mainly use a Cutter for trading, but It's kitted out like a battle ship, plenty of power to spare, engineered shields, armour, shield boosters, weapons and defence modules all top grade engineered stuff. Okay, it's probably considered overkill by some players for a trading ship, but my cargo capacity is around the 528 mark, and there's not many situations in solo where I feel unduly threatened by pirates...but that as I've mentioned it mostly depends on what cargo missions I take on and who I'm trading for. I feel much more confident when trading or doing missions now in solo...I probably wouldn't last five minutes in some open play PVP scenario's with other PVP players though, but at least the npc's are not usually a problem.
Yes, I understand some of the frustrations that the game presents as you're trying to progress, but that also can be alleviated to some degree by not overstretching yourself too much in the early stages, I agree, it's not much fun loosing a ship and also cargo when you haven't got many credits to spare. I've 'lost' perhaps a few dozen ships (perhaps more) over the course of my total gameplay time, and some quite expensive rebuys too!
As for acquiring a Carrier...I personally didn't like or see the reasons for owning a Carrier at first either, but now I've got one I wouldn't be without it. It's
so useful in many ways, especially for exploration and mining.
Upkeep costs seem daunting, especially I would imagine if you only play the game occasionally. I play the game most days, perhaps a little
too much methinks

...so upkeep costs for me are fortunately not much of a priority. You can cover that weekly cost with just a few bio scans, mining, exploration or several other activities within the game.
My Advice is play the game how
you want to play it, but also realise there are limitations within the game if you've not prepared enough in the sense of your ship capabilities. Engineering isn't necessarily needed to bring your ship up to a level where pirate encounters become less troublesome,
but it does make the experience more enjoyable to know you can positively fight back should the need arise. Also If you want to socialise with other players then consider perhaps joining a pve group, If you would rather play in open mode you have to realise there are risks involved, depending on where and when you play. As I've said, I play mostly in solo, it suits me personally for many reasons, but I can also still
influence the game as a whole in certain circumstances, and even in solo I am aware (and happy with) that I'm playing the game with others and not just with npc's.
(I don't have many dealings with Thargoids, as long as they keep out of my way I'll keep out of theirs!

).
Jack