The short answer: It depends.
When you're moving between two languages within the same linguistic group or family, loanwords and cognates can be extremely helpful. This is why Western European languages like German, Spanish, and French are comparatively easy for native English-speakers to learn.
But when loanwords randomly show up in completely unrelated languages (as they often do), the answer is: not so much.
For example, if you know the words tsunami and samurai, then it's technically correct to say that you "already know some Japanese".
But this knowledge won't make the journey of mastering Japanese substantially easier, as I explain in the video that follows: