Feel free to use them as you wish. Make sure to add in your information ("YOUR COMPANY" -> "Puzl Inc."). We are not responsible for upholding these contracts or doing anything other than letting you use them for whatever you want. Also keep in mind that having a contract doesn't mean nothing can go wrong. It just provides something to look back at and enforce if you really need to.
The Worker Contract is used when I hire a new developer. The Client Contract is used for Puzl's clients. All the relationships are contractors, not employees. You'll notice that there are different routes for payments. Feel free to edit those to fit your needs. Also be sure to describe the services provided in more detail. The contracts in the repo are .rtf files. They look ugly so I uploaded the .docx versions. Link is in the readme.
Keep in mind that facsimile (typing your name) signatures are legally binding in Minnesota. I'm not sure on the laws for different states and countries. I suggest using something such as HelloSign, EchoSign, or another signing service if you don't want the hassle of printing, signing, then scanning.