Image Rejection

We here in the Forum are not Adobe employees, so we have no ability to look into your account and look at titles or keywords on your rejected images. Anyway, if something was wrong with your title, it would not have been a "Quality issue". Sharp focus and clarity are missing in your images. Perhaps they were taken with a small sensor camera or mobile camera phone. You would have needed to use a tripod positioned above the floral designs and a wide depth of field to get even focus. The background is also a bit messy.  

To see how competitive this category is, enter "Diwali+flower" in the search box; >40,000 results are shown.

Just so you know what you're up against, Adobe Stock's inventory already contains 26 million perfect flowers of every size, shape & color.  They don't need more unless you have something singularly spectacular to submit.  And it must technically, visually and legally perfect to use commercially.   Otherwise, find something else to photograph.

If you need inspiration, I have put together a list of subjects that customers search for. This may give you some ideas of your own.

https://community.adobe.com/t5/stock-contributors-discussions/how-to-sell-stock-images/m-p/12780712#M41047

Better luck next time.

For your question about the file format,  JPG or JPEG is the same file.

JPG vs JPEG - Know The Difference Between JPG and JPEG (dailyrazor.com)

For all pictures:

Washed out colours, no structure.

In addition, I suppose that you will need a property release for such artwork. The creator of these needs to give you the authorization to publish the decorations.

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