Essa Ilustração foi rejeitada

Your picture is too small to assess the scanning quality, but still, I see some technical issues with the borders. Make sure you do not have visible borders at the top and the right:

As correctly pointed out by @RALPH_L and @reedesign1912, your signature is not allowed on stock assets. This isn't an Art gallery. The buyer needs to be sure to be able to use this for anything he needs it.

I would also allow more border so that the buyer can fit this to his needs. Your dragon is nearly touching the border. This does not allow for an easy reframing.

For this type, you also need to submit a property release, even if you are both the artist and the one submitting this. You simply need to sign for both.

If you are new to stock, you should consider these resources: https://helpx.adobe.com/stock/contributor/tutorials.html
Please read the contributor user manual for more information on Adobe stock contributions: https://helpx.adobe.com/stock/contributor/user-guide.html
See here for rejection reasons: https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
and especially quality and technical issues: https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html

Your name must be removed and you must sign and submit a property release.

What was the rejection reason Adobe gave you?  (e.g. technical issues, missing property release, etc.).  I can see right away that your signature would be an issue as watermarks are not permitted.  If it is technical issues, you would need to post the original image you submitted (not this reduced size version) so we can offer better advice.  Sometimes you can only see the issues when looking at the image at 100% magnification.