Those wires already look like they're shorting! Perhaps there is a current limiter that detects the short and prevents fireworks, but also don't make the motor run.
You should choose suitable cabling for the connector/terminal. If you can twist the strands together and push them into the screw terminal, then it's a suitable wire. If they don't fit, then you need to get a thinner-gauge cable. (I find 16 gauge speaker cable / "zip cord" works great for many medium-size motors up to 10A draw.)
If you are really anxious getting up and running, try stripping 1/2 inch of wire, cutting off half the strands at the insulation, and then putting some heat shrink around the insulation and stripped wire to get the recommended 1/4" stripped wire to push into the screw terminal.
If you have neither heat shrink nor thinner wire, and the existing wire is too coarse, you probably need to go shopping.