The discussion around the significance of Dreadnought typically centers on the gun layout, but there were other elements of the design that made it so significant.

I'll start with the guns. Unlike the generations of battleships before it, Dreadnought stood out in that it had a uniform main battery armament of heavy guns (12-inch in this case). Secondary guns were mounted, but, unlike the older generation of ships where guns of intermediate calibers were designed for engaging alongside the main guns, the secondary armament of Dreadnought consisted of quick-firing 3-inch guns intended to fend off torpedo boats.

The logic behind the armament had several layers to it. In practical terms, a uniform battery simplified gunnery - fire control would only have to account for a single type of gun, and spotters wouldn't have to differentiate between the different calibers of shells falling as they corrected the guns. In parallel to all of this, developments in fire control on ships meant that engagement ranges were rapidly increasing.

Pre-dreadnoughts were designed in an era where accurate fire beyond a few thousand yards was effectively impossible. Gunlaying was typically directed by each gun separately from the rest of the ship, and accuracy tended to suffer as a result. However, these simple fire control systems meant that guns of all calibers tended to have similar effective ranges, so armament was selected to complement the other guns on the ship and cover each other's weaknesses. Heavy guns were expected to do the direct ship-killing, but they suffered from extremely low rates of fire. Medium guns had higher rates of fire, and, although they lacked the punch of the heavy guns, they could devastate lightly armored portions of the enemy warship. The smallest guns tended to be intended for close-in defense against torpedo boats.

Advances in fire control started to change all of this. Central fire direction meant that all guns of the ship were under the control of a single position. Advanced rangefinders meant that gunnery could be directed further out. Longer-distance fire meant that gunners would have to wait until the fall of shot to correct their shots, and for smaller guns this meant they'd be spending much of their time ready to fire but waiting. Torpedoes also played a part in this, as there was heavy pressure to engage at longer distances to stay out of range of a torpedo attack.

The other, arguably just as significant development with Dreadnought was its propulsion. The standard for naval engines up to that point was the Triple Expansion steam engine. However, of all the first-generation Dreadnoughts (South Carolina, Kawachi, Nassau), only Dreadnought bucked the trend, using a steam turbine engine. Turbines were lighter than triple expansion engines and they could run at full power for longer periods. So when Dreadnought was commissioned, it not only had more advanced guns and fire control than any other capital ship, it also was faster and lighter than its contemporaries, all without sacrificing protection or capabilities.

That's say that Dreadnought was particularly out-of-the-box thinking. All major naval powers had generally recognized these trends by the 1890s, and all had been working in parallel to converge onto generally the same idea. If we look at the last generation of pre-Dreadnoughts, we can see this thinking in play - the Lord Nelson and Satsuma class battleships were both designed with larger-than-normal intermediate armament to account for the longer engagement ranges. Dreadnought was going to happen somewhere, the British were just (barely) first to the punch.