We appear to be in the same boat here, you and I. And that said, I can suggest that you stay motivated by not doubting your ability to write. No-one here is suggesting that you're a bad writer, they're simply giving you the harsh criticism needed for improvement. The way I see it, it presents so much of a challenge that the very idea of getting a positively voted SCP on the main list seems like a huge milestone to me, perhaps something that would end up on my CV under "proudest achievements".
Here's an analogy for you. Imagine this site as a large mountain. To scale this mountain, you need to be very strong and inhumanly fit. It's incredibly rare for people to drift in already capable of scaling it, and as such, many people struggle at the bottom for a while. Now imagine that by asking for advice on an SCP, you're asking those higher up the mountain to help you climb it. What are they more likely to do? Carry you up on their shoulders right to the very top, or force you to become stronger?
It's not easy, but when you make it all the way, knowing it was your efforts which allowed you to get there will be all the more satisfying.