Sorry no, not a fig tree. You have some sort of grass, probably a weedy one if it sprang up on its own.

An E-Bay purchase perhaps?

Never buy seeds of common houseplants. First of all, they can send you weeds instead. Second of all, you can buy a good sized tree for $15... hardly worth waiting years to achieve.

brome grass?

Further to macranthos’ comment, if you don’t want to buy a plant, many common house plants grow easily from cuttings, including figs. If you know someone who has one you could beg some pieces.

Ficus benjamina seeds don't germinate on the ground, it's usually on rocks, logs, or on trees. It's possible you may have had the correct seeds which died in the potting soil and grass seeds just happened to also be in there. But as mentioned above, they grow very easily from cuttings.

The grass either sowed itself in the seed pot at some point after planting of the supposed fig seeds or old soil with the grass seed already in it was used to plant the fig seed. If the latter then it serves as an example of one of the reasons to always start off with fresh, unused potting soil - weeds are very good at finding their way into any exposed surface that might possibly accommodate them.

Ficus seeds are like dust almost. Are you sure you got ficus seeds? Ficus is usually propagated by cuttings or air layer. Much easier and simpler.

Ficus seeds can be germinated in a pot and is fairly easy. I have done that for F. relgiosa and F. benghalensis. In nature though they often show up in cracks of walls and on other trees. I think the reason is that on the ground they can be easily dislodged, washed away or out competed by other plants. Crack in the wall is far safer.