Why different computer cord ends?

You can't have some universal connector for any peripheral. For one, different devices have different sizes so that alone constitutes a need for a different connector.

Two, different devices have different uses. Some cables transmit data, electric current or both. Different cables have different electrical properties(impedance, conductivity etc...), quality or internal material(copper, fiberwire). Some of those properties are required by certain devices but not by others.

Try having some little cable that you use to charge you phone be used for data in some server. For that to function properly, the cable must be built to the highest denominator, that is to say that it must conform to the use case of a server. You would end up with a very expensive shielded and twisted cable that would literally cost 500-1000x as what would actually be required for the phone. It's a huge waste of resources, assuming that such a cable is even feasible, which it isn't.

The design, is meat to be idiot-proof, network plug is bigger than telephone modem plug, your USB-A is different from USB-B (Usually used for printers or projectors) HDMI is different from DVI-A even though they both are used to output video, etc...

Hence, you can't plug a USB into HDMI, and people would not be calling tech-support asking why their printer isn't printing. =))