Your situation isn't all that rare for a fresher.
Deciding on a Career Shift
First of all, please don't mix up issues. Whether to go for HR now or not depends on your aptitude for an HR role/job—not on the fact that you began your career in the Marketing field. That will come only later if and after you decide to shift to HR—for which the salary should never be the primary factor—your love for the role/job ought to be the primary factor. At your point in your career (and life too), the focus should be on learning the tricks of the trade, so to say. Money will always follow the one who has the skills, whichever field one is in.
And remember the old saying: "Zindagi mein kuch paane ke liye, kuch khona padta hai."
Considering a Shift to HR
If you really want to shift to HR now, you can do it. But please be ready to begin as a fresher in HR. Also, ensure that you take the experience certificate of this job too—so that you don't end up explaining the gap in your career later on.
Value of Marketing Experience in HR
Also, who said experience in sales and marketing will not be useful in HR? The basic skill most Marketing professionals have is the ability to interact with strangers—which is also required for the usual starting point for any HR person in Recruitment. Additionally, to the best of my knowledge, the procedures used in the Marketing field are usually very systematic, which will be useful to you at any time in your career. I recollect another quote here: "Nothing goes to waste in the learning called 'life.' We only don't realize it while we are passing through that phase."
All the best.
Regards,
TS