How much is considered plagiarism in GCSE music?

I am currently doing gcse music i have started my free composition taking inspiration from a jazz song named "Caravan". I have taken the double bass and put that into my composition whilst slightly changing it to the point where it is still giving a similar sound. Moreover, i have taken the piano and have also slightly changed it to where the pitch varies rather than just ascending furthermore i have simplified it quite a bit. However, the piano is still very complex which i don't know if they will question or anything and i have also taken the key of Eb major and used that. But everything else is different and is made purely by me. Can i please have some thoughts of if i should change anything or it might be fine because i don't want to get put in for plagiarism and failing 20% of my gcse.