camel
駞 centers on the camel as an animal. The single given meaning is straightforward, with no abstract extensions.
駞 combines 馬 (horse) with 㐌, which likely contributes the sound. The exact historical development of 㐌 is uncertain, but the character is used for camel, an animal associated with horses in shape.
The left side is a horse 馬, and the right side 㐌 looks like a hump or a loaded pack. Picture a horse-like animal with a distinctive hump: that's a camel.
For タ, imagine a camel with a tag on its hump: tag -> タ, and the tag identifies it as a camel.