I have gone through several old questions over the last two days.
Some of those have some problems:
Didn't have good answers. Those questions might be answered better now.
Some were outdated. As of 2020, these questions might have more relevant answers.
Some had terrible answers and had positive scores still. Not to offend anyone. Those accounts seem dead.
Question:
What would be a respectful way of drawing attention to those questions and welcoming new answers?
One way would be to post a bounty on them. One of the standard reasons is exactly for these cases:
Current answers are outdated
The current answer(s) are out-of-date and require revision given recent changes.
If you can (suggest an) edit the question to significantly improve it, that will bump the question and maybe draw some extra attention. But you should never edit it in a way that invalidates existing answers or conflicts with the original author's intent.
Finally, if the world has changed so much since asking the question, it could make sense to ask a new question (and carefully explain why it should not be closed as a duplicate, presumably because editing, as mentioned in the previous paragraph, is not an option).
Some had terrible answers and had positive scores still. Not to offend anyone. Those accounts seem dead.
I think for this particular negative aspect of the questions you are referring to, the normal way is to downvote these answers if they are clearly not accurate. The downvote button's tooltip suggests this:
This answer is not useful
Of course, if the account is clearly active, a comment might be a better way to address these answer to allow the author to update the answer.
This helps for inaccurate answers to go down and allow to more accurate answers to go up.
