I am having trouble interpreting the ties in the following picture. It looks like the first four notes in the left hand are just playing eighth notes G, F, C, D. Why do we need ties and those weird looking notes?
They are not ties. They are slurs. It just means play then legato. Note that the bottom notes are also held longer, suggesting a melody in the bass.
The only tie shown is between the two G note (3rd and 4th). The lines are slurs - phrasings.
The bass clef has stems up and down to show that the 1st, 3rd and 5th notes are held longer than they would be with only up stems. It's written as a three part tune - treble clef os top, bass clef/stems up is middle, and bass clef stems down the lowest of the three. the low F lasts for a beat and a half, hence the dot, but the blob needs to be written twice so it can have an up stem too.
The "ties" are actually slurs. Imagine you're singing those eighth notes in the left hand. Sing the G and F in one breath and take a quick breath before singing the C and D. Now sing all four notes in one breath (i.e., as if there were no slurs). You should notice the subtle difference which the slurs make in the phrasing and try to incorporate that "breath" into your articulation when you play the lines. (Alternatively, you could think of a violinist playing the first two notes on a downbow and the next two on the upbow - the point is to play the notes in audibly discernible groups of two rather than as a continuous stream of sound.)
Unfortunately, this is made a bit more complicated because there is a bass line which is doubling the lower note in each two-note motif. Again, try to hear in your head what's happening - two different instruments are playing similar but distinctive lines. Admittedly, it's difficult to bring out the nuances of the two-note grouping while the quarter-notes of the bass are somewhat clouding the issue but that's entirely the composer's fault! The key thing to strive for is a seamlessly legato bass part while slightly shortening the duration of the second note of each 2-note motif so that it creates the illusion of a breath being taken. It can be done but it's a detail which requires very good control and careful articulation.