I'm in your boat so I can't speak for the people who have progressed to the Assessment Centre already.
I haven't been given a "no" which is great!
I'd say they invited the cream of the crop for this first week of testing. Applications closed yesterday for experienced Tower controllers also, so depending on how many applied for that and/or get through their ability and OPQ testing, may determine how many of us still waiting will be invited to the next stage. They obviously need controllers fairly fast so hiring experienced people over training people from scratch makes sense.
In regards to whether you should get on with your life or not, it all comes down to how much you want this opportunity.
For me, that's huge! I've been trying to get in since September 2014. I was invited to an Assessment Centre in 2016 but the Accelerate Program squashed that on me....