Comment by evanelias

You can reproduce and distribute. That isn't even remotely the same as saying you can sub-license or re-license code that you don't own the copyright on.

Source code is generally copyrighted by its author (or the author's employer, in the case of work for hire). If you wish to use, reproduce, or distribute code that you don't own the copyright of, you need a license to do so, and you must follow the terms of the license.

If you include that work in your own derivative work, and you choose to make your derivative work be open source (which is entirely optional with permissive licenses), then for any unmodified portions of the code you must comply with the original license. This is because you are inherently reproducing and distributing copyrighted source code that you didn't write and don't hold the copyright for. You have no ability to change the license on that unmodified code, as you aren't the copyright holder, the license does not grant you ownership, and you must continue to comply with the original license terms to include that code in your open source repo at all.