Julie.chan's response is pretty much on point, but I just thought I'd follow up, as this is actually a vitally important concept that's one of the keys to really understanding Japanese grammar.
How do things happen at present in terms of English language but treated as in the past in terms of Japanese language?
The underlying answer to your question lies in a fundamental point (one that, unfortunately, some textbooks and learning resources gloss over): namely, that "past" and "present" tense as we know them in English
do not actually exist in Japanese.
Japanese has two verb tenses: perfect (what you're thinking of "past") and imperfect (which most native English speakers see as "present" or "future"). So what's the difference? Where past, present, and future tense focus on where the action takes place on a timeline, perfect and imperfect tenses describe only one thing: whether or not the action has been completed (perfect) or not completed (imperfect) relative to a certain point in time.
That's why 疲れた and お腹空いた mean "I'm tired" and "I'm hungry", respectively, and not "I was tired" and "I was hungry". The perfect tense doesn't mean that the actions took place in the past, it indicates that the act of becoming tired or one's stomach emptying are complete.
Note that it's also possible to say 疲れている or お腹空いている. In general, 疲れた and お腹空いた are exclamations made in the moment (i.e. when it hits the speaker that they're tired or hungry) whereas 疲れている and お腹空いている would be used if the speaker has been aware of the situation for a while. 「今日は疲れているから、早めに帰ろうかな」「めちゃくちゃお腹空いているから、がっつり食べられるお店がいい」or the like.
Note that you can also say something like 「ああ～、疲れる！」 if you're commenting on a tiring action or situation. The nuance here wouldn't be "I'm tired" but rather "Man, (doing this) really tires you out." Also, like Julie.chan said, 疲れていた or お腹空いていた are also commonly used to mean "I was tired" or "I was hungry" (at a certain point in time in the past).
This idea of perfect/imperfect (complete/incomplete), if you can wrap your mind around it, will also help you grasp other constructs where it looks like tenses are functioning differently in Japanese than they would in English. In English we can say things like "Ken said he was going to the party" (even if the party itself hasn't happened yet). In Japanese this, would have to be ケンさんは、パーティーに行くって言っていました, never 行ったと言ってました, as the latter would suggest that at the time in question, the act of going was already complete (i.e. "Ken said he
had gone to the party.")
It also works the other way. For example:
赤いセーターを着た男が来たら、教えてください。
If a man wearing a red sweater shows up, let me know.
スパイスをふんだんに使った料理をお出しします。
I'll serve a dish made using an abundant amount of spices.
In these cases, the man has not showed up yet, nor has the food been prepared. But when the man
does show up, he will have already completed the act of putting on the sweater, and when the food is served, the spices will already have been used.
This might be a lot to take in at once, but I encourage you to keep it in the back of your mind when analyzing Japanese verb constructions. Breaking out of the English-influenced past/present/future tense mindset and internalizing the idea of complete or incomplete actions will go a long way to helping a lot of Japanese grammar to "click" for you.