Filtering is necessary to come up with your final list of keywords. 

You have to decide which keywords to use as well as reject. Remember to take into consideration the 100 character (inclusive of commas) limitation of Apple as well as if the keyword is already part of your app’s title or tagline. 

Duplication of keywords is not allowed. 

For every keyword, you need to ask: 

Will I use this keyword? 

Will it generate traffic? 

Is it worth sacrificing space? 

Can I come up with variables / more (long-tail) keywords from this one? 

As echoed by the questions, when filtering your keywords, focus on their traffic potential and not the competition. 

Once you have a clearer picture of what keywords you want to prioritise, go ahead and begin the (sometimes painful) process of deleting keywords from your database until you have your final list.