<p>I'm running a stock Ender 5 pro with the filament that came with it, and using Creality Slicer 4.8.2, but I'm only able to get reliable bed adhesion if I increase the bed temperature from 50 to 60 °C for the bottom layer and decrease the print head speed by about 75 % from the default profile for the Ender 5.</p>
<p>The machine is absolutely stock, and is fresh out of the box except for bed levelling.</p>
<p>I used the default bed leveling print and that came out well, so I'm reasonably certain that it's not a bed leveling issue. The problem seems to be with models that I've made myself in blender and exported as STL files.</p>
<p>In all cases the raft that was generated by the Creality software has printed out perfectly, but the print has only partially gone down when it came to the model itself. <img src="https://i.stack.imgur.com/sdXA1.jpg" alt="enter image description here" /></p>

Assuming Creality's stock firmware still doesn't have Linear Advance enabled, there's a fairly hard requirement to go slow on the first layer. This is because, as the toolhead accelerates up to higher speed without advancing the extruder extra to compensate for the backpressure in the filament-path/nozzle, you'll have an interval of underextrusion, giving less contact area for the extruded material to cling to the bed at the same time there's added force pulling it in a direction parallel to the bed surface. This becomes less critical to adhesion starting with the second layer, since the new material is bonding to itself rather than just trying to stick to a bed.
Having the bed hot will help it stick better and maybe even help reduce the pressure at the nozzle by reducing the heat loss, so it might work around the problem. But in general, you don't want to be in a situation where a few degrees of temperature difference are the cutoff between a failed print and a successful one.
Anyway, do all the usual stuff to improve bed adhesion, and especially make sure your bed height is as close to perfect as you can get it, if you want moderately fast printing to work. But don't be surprised if you need to upgrade to a version of Marlin with Linear Advance (or to Klipper) to get successful high-speed first layers.