set android os version (current api level = 17 )

hi newbie here
I have just setup kitchen and I am trying make my first custom rom from G900FXXU1BOJ1_VDI for Galaxy s5 SM_G900F
kitchen is asking to set current api level which is saying is level 17 (Android 4.2.2)
this rom G900FXXU1BOJ1 is for Android 5.0 which is api 21,
Android 5.1 is api 22 and Android 6.0 is api 23,
so my question
is there any point in setting the api level higher than 21
thanks

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