I am aware that I can rarely ever offer anything of value in terms of answer to questions. I feel bad about this because I should be giving back for the free help that I receive. Does not answering questions (and not always asking amazing questions) make me a "poor" user and how can I redress the balance?
While you may not have the super-duper 10 million dollar answer to every question on the site - there are several ways in which you can contribute back. Offering helpful flags on [ duplicate | spammy | off-topic ] questions, edits to improve grammar, and most importantly - up votes!
Giving away karma on the site encourages the users that are doing a "good job" - to continue doing a good job. The gamification of the site is still a major factor in new engagement.
While you may feel like you're not giving back - the fact you contribute and have enough presence to ask if you can be doing more - tells me you're a great user and you should feel good about yourself every time you click that up-tick on an answer and a question. That's the best thing anyone can do here aside from maybe answer the impossible. (which seems like someone does before I show up... snap)
Keep your chin up and know you're a valuable member of the community. Cheers
No, of course you are not a "poor" user!
The fact that AU has helped you does not mean that you have to devote your life to us! ;D
We appreciate if you help running the site by asking, answering, editing and/or reviewing with as much knowledge and time you have or want to spend, but you don't have to repay any "debts".
By the way, maybe the statistics make you feel better. You're not that bad if you take into account how many users with only 1 rep come and leave every day. Of course you may not compare yourself with "god" Oli!
So no need to worry about anything. We're proud of you as well as of all the thousands of other active members!
The only way you can be a “poor” user is if your posts steal away the attention from others, or steal the time of other users, without giving anybody something helpful. Fortunately, the StackExchange sites are designed with many safe-guards against this, including the voting system. Questions that don't interest anybody won't receive upvotes or replies and thus won't linger long in the “active” list, so the time they take isn't much of an issue. Some users have posted two or three questions that weren't helpful to anybody, and not committed any other activity – but I still wouldn't call those users poor; perhaps neutral would be the right word: they don't have any positive impact, but not really any negative either.
Only when posts are excessively bad (so they hinder people from efficiently searching for solutions to their problems) and/or users post excessive amounts of useless stuff, there is a need to exclicitly downvote/flag/close. Should this happen to you – well, then you should perhaps think about changing your behaviour. (But don't one or two downvotes scare you! Sometimes this just happens...)
Otherwise – you're fine. Indeed, when you do as little as any (reasonable) voting/flagging, or ask but a question that somebody found interesting, then you're being helpful. You may not be a top user right away, but there's no reason why you should have to be – any net positive contribution makes you a good user.