When one thinks of earth they think of strong, solid, and firm. In this element, much of the techniques possess those basic properties. However, there is more to earth release simple structures. We’ve seen earth release manipulate the structural foundation of earth to change it from solid to a liquid (like Swamp of the Underworld), convert it into sand, or manipulate alternative forms of earth like certain metallic entities. There has also been manipulation of the physical earth itself, changing the structure of the earth, using shape manipulation to reconstruct and mold. The earth nature within their own body allows them to create manifestations of earth out and around their bodies, essentially creating their own earth.
Earth is a versatile element because we walk on it. Mostly everywhere you walk, you will be able to use earth techniques, which gives a great advantage against water users. It is a solid element with great crushing and piercing characteristics. It has a tremendous amount of use which is why it has the most techniques, I think. It's projectiles possess a great force because of their mass and it's proportional to the increase of acceleration. The faster you throw a rock or pebble, the more it will hurt. Earths' main weakness is lightning, due to the fact that Lightning is so fast, strong, and unstable that it just tears through Earth's solid core, and shatters it, while it's strong against water because it can split water waves, redirect them, push them back, etc. It's a great combination with fire because Earth turns Fire into lava or in case you have mud, it hardens it. I would say Earth is neutral too Wind, unless the Earth is not solid, like Swamp of the Underworld. Then a Wind can blow it away much like you could a Water jutsu.
Earth techniques are diverse as mentioned above because it has a paramount of supplementary, offensive, and defensive options. For a supplementary use, one can manipulate the earth they are standing on to create tools of earth such as shields, swords, canes, staffs, etc. We can also change the characteristics of our bodies with earth, just like The Third Tsuchikage did with himself which can enhance your speed or durability at will with a touch. One could also shake the earth and nock your opponent off balance. For a defensive use, we can use the earth around us too create pillars of earth too defend against incoming attacks, create domes of earth too protect us against liquid attacks like water or lava, since the dome would be more solid and liquid attacks go around solid objects. Another defensive characteristic earth users have is that they can change the properties of their bodies into diamond like skin, as shown when Kakuzu did it again Kakashi Hatake, but we would be even weaker against lightning attacks. For offensive purposes, we could use the earth under our opponents for quick attacks, like making a pillar beneath an opponent. We could change the property of the earth under an opponent to a swamp of some sort too drown them also.