If the thing in this pic is a fishing spear, it's a whaling harpoon.
It's awfully big and blunt to be something thrown or shot - I'd think it more likely a striking or pounding tool, but it does have a few notches where it might be a little sharp... maybe a scraping tool? But, I would think this would be smoother.
We used to have access to a farm field where we could find up to a dozen well worked pieces in a couple of hours. We might get two or three intact, perfect points, and 8 or 10 broken points. My brother-in-law who farmed it literally had 3 or 4 five gallon buckets full of worked pieces. He had several flat, drilled pieces that looked like stone jewelry, axes, and at least one very nice matched mortar and pestle he found in that field. It was simply amazing. We found little caches of round river stones away from the river - someone we knew said these were used for cooking... that the stones were heated in a fire and then dropped into a leather bag with food and that this is how some foods were cooked, with the heat of the stones rather than over the fire.
With some small experience and second-hand hear-say knowledge in this, what I am seeing in this photo is not a well worked piece, it's kind of rough. It does not look to me like a 5000 year old piece, but I'm no expert. I do absolutely think it looks like a worked piece though. My guess is that it is what I call a "blank." I've never had this confirmed by any expert, but I found SO many partially worked pieces like this - and often found them in groups - that I developed the idea that the owners worked these pieces in sessions. I don't think they sat down and made one perfect piece at a time. I think they sat down and worked a bunch of pieces at one time, working them down to remove all the "waste" and to lighten them. I think they finished whatever pieces they needed right away, and then kept some partially worked pieces handy that they could finish quickly when the need arose.
Let me stress this point: I could be completely blowing smoke and telling a lie here. I do not really know anything of the sort. BUT - I did often find what seemed like stashes of partially worked pieces so that it appeared to me someone left them in a handy spot to finish later.
I do not mean to minimize what you have found. It is really exciting to find this kind of stuff, and even after finding many such pieces it gets addictive. This is all the more true when you find a site that produces lots of pieces with only a little work.
These people needed all kind of tools, not just arrow and spear points. They made stone bowls and grinding stones. They made very fine points for piercing leather. They made hammers and axes. They made jewelry and adornments out of stone. They developed great skill at working stone to create sharp edges and utilitarian shapes. This photo doesn't look like a finished piece to me, but again, I have to admit my experience is limited to pieces found in one particular spot near the Conowingo river in Maryland. But, these people used similar kind of stone - there was no local flint to make the kinds of amazing points that you find in other regions where flint was plentiful.
I found literally hundreds of pieces in this same field over a period of about five years, all of this kind of stone. One time and one time only, I did find a flint piece that was shaped very differently from the common local pieces. This was one of my most exciting finds, because it could not have come from that area, and made me think that it must have gotten there through some sort of trading network. You get a much finer and sharper edge with properly worked flint - and I have to think that if a local person had gotten a fine flint tool in a trade that it must have been a real prize to him. When you spend time finding stuff like this, you cannot help but really fantasizing about the lives of the people who left these tools behind. It really transports you.
So, let me end by saying congrats. It's very cool to find this stuff. We lost access to the farm field where we used to hunt, and it left a hole in our summers for years. Searching that field was one of our favorite weekend activities in the seasons when the fields were freshly plowed up and after a good had washed the loose dirt down.