So these two events, soccer and room one are dependent, before they were independent, but now they are dependent. In the example that we did previously, the kids were split randomly.

Lets take example of dice,

Probability of sum is 10 given first one is 6

Now the answer is \frac{1}{6} because we have only one case (6, 4).

But if you will do the experiment, it is still random. Because we calculate probability of random processes and events.

but that randomness of probability is dependent of each other, so it cannot be random.

you are probably confusing probability here as randomness which is still an estimation of might or might not, that is why it cannot be random.

randomness is considered when we know we are choosing a particular dice from a set of known dice of outcome. Here we don’t know if the dice (or coin is head or tail), so it cannot be random.