You did a good job separating the interior wires to increase their surface area with the solder. Splaying out the bristles allows the solder to penetrate the whole wire and enables a good connection. You didn’t make the Arecibo collapse mistake.

You have a lot of small chunks with poor interconnectivity. It’s like you dripped solder onto the wires and let each drip cool before the next one landed. Try remelting the solder into a contiguous pool and letting it reform the connection. Maybe even add more solder so there is enough to coat the available surface.

The only structure holding these wires in place is the solder. Try poking some of the wire bristles through the holes that you are trying to make a connection with. Aim for a closer connection between the wire and the breadboard, and structural integrity against impacts. Compared to your wires attached next to the conductive holes, a wire threaded through a hole that gets knocked around is more likely to end up in a new position that remains in contact with the hole.

Make a solid and strong connection using the structure of the the materials, then add solder to glue it into place. Look at how the clips on the components that you are attaching to use their shape and rigidity to keep pressure against the conductive holes. Make sure that the solder fully melts and makes a contiguous connection.