Can I fit my normal brake levers to the curves of the dropbars? I ride Firefox Rapide 21S, a hybrid bicycle.
It has factory fitted flat-riser handlebars with Shimano EF500 levers for V-brakes with gear shifter integrated.

I am an unprofessional rider, I always liked riding fast, I gained knowledge about dropbars and actual road bikes after getting this one, as I realized I needed more to go faster.

I was recently thinking about fitting a dropbar to it and then mount my existing levers onto the place of hoods, as it goes beyond my budget to purchase them.

Will it be a good idea to do so?
Will it even work if I tighten it really hard so it doesn't slip?
Or, just not get into this mess and I'll be alright with fitting them on the flat portion of the bar?

I'm also attaching images of levers, but not dropbar(I haven't bought them yet).
Sorry, but fitting drop bars to a flat bike is a no-go.

The flat bar levers will not fit properly on a drop bar. You will probably not be able to reach the levers easily which is dangerous ! Reaching the shifters will also be difficult if not impossible.

The other reason is that frames designed for flat bars are longer than those designed for drop bars, as the drop bars extend the hands further forward. You likely find that the hand position on drop bars on a flat bar frame is too far forward.

If you want to get a somewhat faster more aggressive position but retaining you brake lever and shifter hardware, consider replacing your riser bar with a flat, slightly narrower one.