First-year PhD giving a talk among well-established researchers in the field

Let's flip this question around and imagine that you, as a first year anthropology PhD student, are now visiting your high school. One of the students asked your former teachers if you would be interested in a local, anthropology-related research project they were doing (e.g., they could be investigating the attitudes of people towards those who are HIV positive, and contrasting how that varies between countries). The teacher promptly arranged for them to give a talk on their results while you were there.

The student feels excited but afraid at having to give this talk. She knows she doesn't have the pedigree you have, she doesn't know if she should apologize, maybe you don't know she flunked her latest exam, and she thinks she is not deserving to be giving the talk because she doesn't have as much experience as you. Should she go ahead and give the talk or would it be counterproductive to her future career?

I'm pretty confident you will say she should go ahead, and the same applies to you. These well-established researchers probably know (or can tell) you're a PhD student, and will not demand that you have done groundbreaking work on par with theirs. Instead of focusing on all the things that could go wrong, think of all the things that could go right: you get to present your work to a well-established audience. They're the people you most want to know your results. You get to network with them. You get to practice skills that you'll undoubtedly need later in your career. What's the worst that can happen anyway? Even if you give a truly atrocious talk they'll probably all have forgotten about it by next year.

tl; dr: stop worrying and do it.

1. The conference organizer thought you had enough snap to run a presentation to this august body. Given that you have a previous and good relationship with the organizer I discount that you are being set up for failure.
2. You had planned to submit a paper. Your paper was going to be among papers of the elite. This is nerves. At the worst while speaking folks will just check their email and converse in low whispers EXACTLY like they will do to some of the most well-established researchers in your field.
3. (Actual advice) Go back to the organizer and express both your desire at the opportunity and your concerns. They are the organizer and it's their job to balance these things. The feedback will be valuable and should help in whatever decision you make.

Go ahead and present (the whole point of conferences and workshops is to give and receive criticism on your and others' research)

Academia should be about ideas and research, not "status". If you have good ideas and are producing good research (NB: I say "producing", which is not necessarily the same thing as "publishing"), you should not feel embarrassed. Of course, it is often difficult to ascertain how good your own work is, which is precisely why we convene things called "workshops", "colloquia", "round tables", and, for that matter, conferences. Go ahead and present on your work, and go with an open mind that is receptive to what others have to say about it (although that does not mean you have to agree). You should trust the convenor's judgement in having invited you to present (and besides, if the convenor made a mistake, this is your opportunity to make a big break, just like Monet did when he was mistaken for Manet!).

Part of the remit of these fora is to encourage intergenerational dialogue on work-in-progress. And, by the way, the quantity of publications do not necessarily correlate to the researcher's ability. You should spend less time thinking about "keeping up with Jones's publication record" and more time thinking about your research.