Black line across top of all my developed pictures

What's the problem? That's the way the camera is supposed to operate. The Live View feature, which lets you use the LCD for framing your picture, wasn't introduced until a later model.

If we assume that the lens cap has been removed for the pictures, then you have other issues. The shutter is not opening. Why?
1. mechanical issue like something broken, bent, jumped out of the track.
solution: repair shop

2. electronic issue like exposure module died, misreading exposure sensor, flash not raising and firing, etc.
solution: repair shop.

Repair shop will also Clean, Lube and Adjust.

If the affected photos were taken using a flash then you simply had the shutter speed set too high. The fastest shutter speed you may use when using flash is 1/90th of a second; with anything faster the second shutter curtain starts to travel across the film plane before the first one has fully crossed so only part of the negative is exposed.

If they were taken without flash then your camera has a faulty shutter assembly which must be replaced. It's not a DIY job, it's not cheap, and on a consumer grade 35mm SLR like any of the Rebel/EOS triple digit models it's usually not cost effective. Especially when there are millions of them lying unused and regularly available for next to nothing on auction websites and for absolutely nothing on FreeCycle/Freegle.

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shutter problem, cut off is part not exposed,replace the shutterunit.

One of the shutter blades is faulty or is being obstructed. Either that or you're using flash to take pictures but using too fast a shutter speed, most SLR's have a flash synch speed of 1/60 or 1/125 of a second.

The first problem will need a professional repair, but it may be a fairly straightforward one. The second problem would require that you read the user manual for both the camera and flashgun.

Your camera has a faulty shutter or shutter timer.

Given that you can buy a perfectly good Rebel S for anywhere between £1 to £25 on Ebay it's not economical to repair it.

Check for the settings of the camera .Open the back door of the camera now press the button seeing through back, if the shutter opens up and closes everything is correct.
check for the film.

You set the shutter speed at 90 when you are using with flash.If you set 125, then half frame would come

The shutter is most likely damaged.